I don’t think this can work. A threadiverse community is contained by its instance and rules. A hashtag pulls everything from every instance so it’ll get unwieldy fast.
From the threadiverse point of view it would make a bit more sense to be able to follow specific microblog accounts as a way to get that content here. Microblogs (or at least Mastodon) are doing their own equivalent of that already because they can interface with threadiverse communities natively (they’re presented as groups that boost every new post & comment).
There’s Kodi in WebOS brew appstore. I’ve only ever used Kodi for offline media libraries but as far as I know there’s plenty of third party Kodi addons for this kind of piracy.